Did you try Google?

Can you specify what you are trying to react the polyurea or polyurethane with? Adding amines to a polyurethane can produce polyureas. One method is to block the reactive linkage, such as - N=C=O, then mix with your reactant (amine?), and slowly heat the mixture. There will usually be some free isocyanate groups, and they will react, until you reach the unblocking temperature and free the isocyanate linkages. This is the basis for coating magnet wire with phenol-blocked polyurethane - polyester mixtures at very high speeds in a furnace, such as GE has used.

It might be possible to "just cool it." Chemical reaction rates double for every 10 degree C rise in temperature, and the reverse. Possibly you could keep your existing system and refridgerate the reactants before you start. Of course the reaction generates heat as it runs, but maybe you can achieve your goal with this simple strategy.

Good luck.

One can titrate aa amine Rx between a polyurethane or isocyanate, it's that fast. Sec amines are slower, but not significantly so. Many of the polymeric Rxs would be too viscous to run much below room temp.